A customer is installing these SAG Fighters in front of panelboards. The question is how do we model this in EasyPower power software ?
From the literature it's a Dynamic Voltage Restorer...
A guy at an established site (not new construction) got up in a mechanical lift doing some retrofit work, that goes on continuously at this site.
Many of the tray cables coming out of the elevated cable trays have only strain relief at the tray then onto their conduit that extends up from the...
A 200 Amp overhead service feeds an outdoor 200A fused disconnect on the outside of the house. Circa about 1960.
3 - #3/0 wires in metal conduit go from that disconnect, through the crawlspace 50', to a 200 Amp panel board in the middle of the house.
The conduit is bonded with a short piece of...
We are trying to do a hot switchover of this 15kV bus that is fed from two different sources. I've tried to model it with EasyPower software.
According to the software there is a 400V difference between the one system and the other. Is there a problem doing this?
We have a 150 kVA dry type transformer that is a part of a bigger packaged unit. That question came up.
The transformer case will be bonded, there will be equipment grounding conductors run between the panel feeding it and the transformer.
Looking at the NEC 250.4 ... it doesn't appear this is...
Basler provided printouts of their relay settings for new relays that replaced old ones in some old switchgear.
They specified E2 - IAC Extremely Inverse. EasyPower does not have that pick. It has: E2 - Extremely Inverse and C1 - IEC Extremely Inverse.
Note they specified IAC ... which isn't...
On a recent project an old 15 kV fused switchgear was replaced by new switchgear that uses HV vacuum circuit breakers and SEL-351S relays on the feeders that land on step-down transformers. Looking at the curves for the new feeder relays vs old E-rated fusing … the instantaneous setting for the...
The Utility says the available short circuit energy is 6964 MVA at 138kV at their substation. The 3-phase fault value from the Utility is 29.38kA.
6,964,000,000 / (138,000 * 1.732) = 29,136 Amps ...close to the value given. I'm not used to dealing with transmission voltage levels, but doesn't...
Have been asked to make modifications to the existing 125VDC hard-wired control system at an industrial plant. Below is a portion of that control. It looks like the Amber light drops the voltage to less than the threshold voltage of the control relay that's in series with it. Should an alarm...
A new rectifier system is installed on an existing unit substation as the simplified sketch shows below. The 45A thermal magnetic circuit breakers that feed the small rectifiers trip shortly after the system is powered up. They heat up to 150 degrees F per infrared testing. We measured the THD...
Looking at a proposed electrical design....they've got an SPD connected right at the new switchboard through a branch circuit breaker.
I'm thinking perhaps this just for disconnection means.... but they used a #6 wire on a 100A trip. #6 is too small for a 100A circuit breaker normally. But if...
We have a small project to perform a power study for a new waste water facility. In the project documents they are specifying a new 750 kVA, 12.47-480V pad mounted, oil filled transformer. But they are NOT specifying new fuses in the HV terminal cabinet of that transformer. Is this the standard...
There is an existing overhead utility line that feeds a 12.47kV-480V, Delta-Wye 2500 kVA transformer that has E-rated fuses at the primary of the transformer. For reliability they are changing this feeder out and running underground cable directly from the Utility's switchgear to a new 12.47kV...
Does anyone have a chart or something to back up where this info comes from ?
For example...
On a 480V bus the selection in EasyPower is either 25mm (.984 inches) or 32mm (1-1/4")
On a 34.5 kV bus the electrode gap is defaulted to 254 mm (10 inches)
This effects the calculation.
At present this building (originally built as a warehouse) is fed by two services. One is 480/277V three phase 4-wire which mostly feeds lighting panels and the utility loads for the building itself. The other is a large 480V, three phase 3-wire service that was added when the building was...
Below is a sketch of a service from a Customer owned 12.47kV-480V transformer. There exists another service that comes into this same building that feeds the 277V lighting loads. That total load is no more than 200Amps, 480V, 3-phase. This is being re-worked so that there is only one service...
There is a new 12.47kV primary line being fed into a new 15kV power circuit breaker with a 751SEL relay. The power circuit breaker feeds a 2500kVA outdoor pad mounted transformer. The transformer is a 2500kVA, Delta-Wye, solidly grounded, 12.47kV-480/277V. The transformer feeds a low voltage...
We think this company went out of business. But we are trying to convert some old files that were done in this software 20 years ago or so. Any suggestions?
In the Red Book there is this statement about the below circuit.
"It is good practice for transformers of the size shown on the incoming service, where a circuit breaker is used on both the primary and secondary sides, to install percentage differential relays and inverse characteristic...
In the IEEE Red Book there is this statement that it does not clarify. Can someone explain?
"When applying a current-limiting fuse of a given voltage rating over 600V on a circuit of a lower voltage rating, consideration should be given to the magnitude and effect of overvoltages that will be...
